Making a custom Brawl for Dolphin. Need just one more step.

[Astal]

After following the instructions in this and another video, I can play project M o problem
The trouble is, I want to use my own hacks. The costumes I put in work in Project M, but when I delete everything else, the game locks up when the battle starts. What do I delete or change so I can basically have a fresh Brawl that I can just copy files into?
Project M - Dolphin Set-Up Tutorial